The present inventors previously discovered that Microellobosporia grisea, an actinomycete, produces a polysaccharide, D-manno-D-glucan (DH-6665F), having anti-tumor activity and succeeded in separating and purifying the same as disclosed in Japanese Patent Application (OPI) No. 155201/81 and reported in Carbohydrate Research, 114 (1983), 164-168 (Elsevier).
However, in some cases, D-manno-D-glucan (DH-6665F) (hereinafter referred to as "mannoglucan") caused side effects such as transient pyrexia.